Biomedical subjects

S R Muñoz

Publications and source records attributed to S R Muñoz.

6 recordsLinked to original sources

PubMed2001

Growth in indigenous and nonindigenous Chilean schoolchildren from 3 poverty strata.

OBJECTIVES: This study sought to determine whether the short stature of Mapuche children, an indigenous group in Chile, reflects poverty or genetic heritage and whether the international reference population, derived from studies of US children of mostly European origin, is appropriate for assessing growth failure in indigenous peoples of the Americas. METHODS: The study assessed 768 schoolchildren of Mapuche and non-Mapuche ancestry, aged 6 to 9 years, living under conditions of extreme, medium, and low poverty. RESULTS: Growth retardation was strongly related to poverty in both ethnic groups. Within poverty levels, there were no significant differences in stature between ethnic groups, and in low-poverty areas in Santiago, the capital city, mean stature was only slightly less than in the reference population. CONCLUSIONS: Poverty, not ancestry, explains the short stature of Mapuche children, and use of the international reference to assess growth in this population is appropriate.

Body Height↗

PubMed2001

[The use of state of the art statistical methodology in biomedical research: the example of methodology for interim analyses in clinical trials].

BACKGROUND: Clinical research stresses the need for evidence as a basis for setting research agendas. The extent to which current clinical research involves recent advances in biostatistics is not well known. AIM: This manuscript focuses on the use of interim analyses accumulating data in clinical trials. MATERIAL AND METHODS: A PubMed search was conducted for the period 1990-2000. Keywords used included 'interim analysis', 'alpha-spending function', and 'early termination', after subsetting to 'randomised controlled trials (RCT)' that were 'multicenter' since these particular studies are more likely to have external monitoring boards conducting interim analyses. Studies were grouped by clinical discipline and also by journals of high or low impact index. RESULTS: Thirteen thousand two hundred eighty two articles with both 'RCT' and 'multicenter' were found. Of these, the 'interim analysis' keyword yielded 879 articles, of which only 163 (19%) studies reported their methodology. The percentages varied by clinical discipline and by journal type. A 25% random sample of the articles were further reviewed to investigate the appropriateness of the interim analysis methods used. DISCUSSION: Recent articles in the medical literature attempt to make the interim analysis methods more accessible to clinicians. However, further training of statisticians involved in clinical trials is needed as well.

Clinical Trials as Topic↗

PubMed1997

[Measurement of reliability and validity of clinical instruments].

In biomedical measurement, comparisons between two instruments or between a new instrument and the gold standard is commonly needed to evaluate the reliability and validity of the instruments. Such studies are frequently analyzed using statistics that are inappropriate for studying concordance. This article reviews the appropriate statistical techniques and provides a current methodological guide for the evaluation of reliability and validity of instruments used in the measurement of biomedical variables. The techniques are illustrated using real data from a pilot study comparing four instruments for measuring cholesterol.

Blood Chemical Analysis↗

PubMed1996

Nonfatal and fatal firearm injuries in a rural county.

OBJECTIVE: To measure the incidence of fatal and nonfatal firearm injuries in a rural setting. DESIGN: A prospective, population-based surveillance system using information from medical and legal records, newspapers, and members of the community. SETTING: A rural county in North Carolina. MAIN OUTCOME MEASURES: Incidence rates and case-fatality ratios (fatal:non-fatal). RESULTS: Of the 114 firearm injuries detected by the surveillance system from January 1, 1990, through December 31, 1991, nearly two thirds were nonfatal. The overall age-adjusted annual incidence of firearm injuries was 66.4 per 100 000 population, and the incidence of nonfatal firearm injuries was 41.2 per 100 000 population. Subgroup annual incidence rates were greatest for African Americans. The overall case-fatality ratio was 1:1.8 (fatal:nonfatal). CONCLUSIONS: Incidence rates and case-fatality ratios for firearm injury in this rural setting were greater than expected, based on national estimates, perhaps because of greater proportions of rifle injuries and self-inflicted injuries.

Accidents↗

PubMedDate not supplied

[Sample size for estimating attributable risk in cross-sectional studies].

The prevalence of a variety of risk factors and their strength of association with a disease can vary greatly among apparently similar communities. In small communities, risk estimates can also vary from year to year. An identification of important risk factors in each community is then needed, so that interventions can be specifically oriented towards the needs of each specific community. The attributable risk is the adequate measure of association for these purposes. The purpose of this paper is to determine the minimum sample size required to detect a given attributable risk in cross-sectional studies. A table was constructed, presenting the number of exposed subjects necessary to detect a given attributable risk for different combinations of prevalence of disease and prevalence of exposure to a given risk factor, with a power of 0.80 and alpha of 0.05.

Cross-Sectional Studies↗

PubMedDate not supplied

[The case-control design in medical research].

The aim of this paper is to present a conceptual and practical framework of the case-control design in medical research. To illustrate this method, practical examples directed to clinicians and other health professionals interested in medical research are presented. The case-control method is very versatile and allows for multiple applications. Guidelines for the selection of cases and controls, and some considerations on sample size are presented. In the statistical analysis we use concrete examples of how to estimate odds ratios, confidence intervals, and methods to control for potential confounders, from stratified analysis to logistic regression.

Case-Control Studies↗